Turbogenerator



July 22, 1924.- 1,502,065

A. w. SMITH TURBOGENERATOR Filed Dec. 24. 1923 M INVENTOR;

Patented July 22, 1924.

PATENT OFFICE.

ALBERT W. SMITH, OF LOS ANGELES, CALIFORNIA.

TURBOGENERATOR.

Application filed December 24, 1923. Serial 1%. 682,591. a

To all whom it may concern:

Be it known that I, ALBERT W. SMITH,

a citizenof the United States, residing in the city and county of Los Angeles and State of California, have invented certain new and useful Improvements in Turbogen-. erators, and the following is a specification thereof.

The design, construction and operation of 1 the turbogenerator, has heretofore been greatly restricted, and the output, unit capacity and efficiency thereof thus limited, by the efiects of heating and rotor windage therein.

To avoid heating in the generator, I therefore employ a water mist to absorb the heat losses by radiation therefrom, the same be; ing formed in the generator at the temperature of the boiling point therein, and at the rate required to maintain the necessary radiative temperature above that of said boiling point therein. Said boiling point water mist, due to its high thermal capacity in the hotter generator, thus having the ability to maintain a uniform and practically constant working temperature therein, together with the inability of wetting and shortcircuiting the same. The use of radiative cooling for the generator, also has the advantage of permitting the vacuum operation thereof to minimize the windage loss therein, and thus to enable the use of the twopole design therefor.

In the drawings herewith, my invention is shown as applied to a twopole generator, Fig. 1 presenting an axial section, Fig. 2 a cross section, and Figs. 3 and 4 detail views thereof.

For a vacuum operated generator it is desirable to so arrange the closure and the airsealing of its casing, as to permit the rapid opening and reclosing thereof, for inspection and repairs to the generator when needed. To these ends the casing. is formed of the box frame 1 and the removable hood 2, the frame 1 serving also as a support for the stator 3 as shown in Fig. 2, while the rotor 4 is journaled in the usual type of bearings, not shown. To avoid the use of clamping bolts for the hood 2 and stator 3, the action of the atmospheric pressure on the hood is employed to retain the same in position, the hood being formed with a bearing on both the frame 1 and the stator 3 as shown in Fig. 2. While to support the flat sides of the hood 2 against the crushing action of the atmosphere thereon, the same are braced against the stator 3 by a series of rods 5 as shown in Fig. 2, said rods being driven into contact with the stator, through holes in and then welded to said hood. To airseal the vacuum casing, I employ the well known type of water glands 6 at its shaft passages, as shown in Fig. 1, and the parafline or other waxlike seals 7 at its parting joints, as shown in Fig. 2. To form the seals 7, the jointfaces of the casing are served with parafline or other waxlike coatings, which, by welding together by the pressure of the hood 2 thereon, form a perfectly tight and elastic airseal therefor. While to facilitate the welding and unwelding of the seals 7, I employ the heating coil 8, which is let into the joint face of the hood 2 as shown in Fig. 2, and the passage of a heating current through which softens the seals 7 as required. And it is thus seen that by the softening of the seals as described, the unbolted casing of the generator can be quickly opened and reclosed, after first removing the water glands 6 therefrom.

To obtain a high vacuum for the generator, I connect the same by the pipe 9 with the turbine condenser 10 to obtain its vacuum therefor, and also employ a series of high velocity steam jets 11 in said pipe, to eject the water vapor formed in the generator therefrom, and thus to raise its vacuum over that of the condenser. To form the jets 11 the well known type of multiple jet expanding nozzle 12 as shown in Figs. 1 and 3 is employed; and, as the velocity of the jets is thus far greater than that of the vapor molecules due to their kinetic energy, the motion of the latter is accelerated and directed by said jets, and the vapor is thus ejected from the generator to the condenser as required.

To form the boiling point water mist in the generator I employ superheated water therefor, the superheat in the water thus acting by flashing off therefrom as it enters the generator, to atomize the same into a' fine water mist at exactly the temperature of the boiling point therein as required. The water may be drawn from any convenient source having the necessary superheat as referred to the boiling point in the generator, to insure its complete atomiza-' tion as it enters the same. While to distribute the water and the resulting mist in the airgap of the generator, I supply the same by means ofthe pipe 13 tothe header 14 and thus to the spray pipes 15, which are spaced apart in the airgap as shown in Figs. 1 and 2, and'a number of fine drill holes, in-which as shown at 16 Figs. 1 and 4t, serve to form the mist jets 17 as shown in Fig. 2. While the windage current of water vapor in the airgap acts to quickly distribute the mist thus formed to all parts thereof, for the rapid and uniform cooling of the generator by the radiation of heat from all parts of the airgap surfaces thereto.

To -control and limit the cooling action ofthe water mist in the generator, and thus to constantly maintain the necessary superboiling point working temperature therein,

I supply the mist forming superheated water at the required limited rate by means of a needle valve 18 in the pipe 13 thereto, the same being manually adjusted by the generator or switchboard attendant, to maintain a practically constant working temperature at the airgap surfaces of the generator, as indicated by an electric thermometer comprising the imbedded resistance element 19, the battery 20 and the indicating head 21. Or if preferred, any well known type of temperature responsive mechanism can be employed for the automatic operation of the needle valve 18. And, while radiation from the generator to the boiling point water mist takes place at all superboiling point temperatures thereof, I prefer to operate the same at a temperature sufliciently above that of the boiling point employed, and as determined by experience, to insure a rapid and positive cooling action therein.

The high thermal capacity and non-wetting property of the boiling point water mist in the hotter generator, is due to its complete loss of molecular cohesion at the boiling point, the same thus having the ability due to its rapid vaporization, to absorb heat at a practically unlimited rate from the hotter generator, together with the inability of wetting and shortcircuiting the same. And from this it will also be seen, that due to the resulting inability of the mist particles to touch the hotter airgap surfaces, the presence thereof in the generator can not in any way affect its windage loss, which. therefore is solely determined by the slight friction of the low tension water vapor therein. From the foregoing it will be seen, that in view of the inevitable variation of the vacuum and boiling point in the generator from various causes, the use of superheated water to form the boiling point Water mist inside the generator, and thus at exactly the temperature of the m0- mentary boiling point therein forms a highly important feature of my invention.

scribed, has the highly important advanta e of absorbing the heat losses thereof direct y from all parts of the airgap surfaces, and thuswith a minimum flow of heat in the generator and no cross flow of heat in the cores thereof, all of the core loss flowing radially along its laminae and directly to the airgap surfaces, while the loss of the windings flows into the core teeth and thus out to the airgap surfaces, the heads of the windings being also cooled directly by contact of the rotor windage vapor current therewith.

The principal advantages of radiative cooling for turbogenerators are, the avoidance of all heating and hot spot efiects therein, also the absence of all wetting and shortcircuitingrisk therein, and the ability to employ a simple, compact and ductless construction therefor. While the principal advantages of vacuum operation for the generator are, the ability to design the same for maximum speed operation due to the reduction of the windage loss therein, the windage loss in generators of large size, though operated far below the maximum speed, being as high as a thousand horse power. The avoidance of fire risk in the vacuum operated generator also is an important advantage, while the lower boiling point and working temperature therein has only the relatively unimportant advantage of a somewhat lower resistance loss in its windings due to the lower working temperature thereof.

The operation of the generator is as fol,- lows: Assuming the same to be started and to be. driven at its normal speed, and the vacuum boiling point therein to be at about 50 F. If then the valve 18 is opened the superheated water will be admitted to the spray pipes 15 and a water mist at the temperature ofthe vacuum boiling point in the generator, will be formed in and distributed to all parts of the airgap as described. And

if now the generator is excited and loaded,

its heat losses however great, will be in: stantly radiated to said boiling point water mist, and rendered latent by the vaporization thereof. And, by the control of the water supply to the generator, by means of the valve 18 as described, a uniform and practically constant working tem erature of about or F. can be positively maintained at all arts of the air gap "surfaces, while the windage loss of the generator will bereduced to that of the slight friction of the low tension water vapor therein, and all noise, shortcircuiting and fire risk therein also will be avoide And it is thus seen that due to the practical absence of rotor windings, and all heating and hot spot eflects in the generator, its rotor speed is now limited only by the currentv frequency employed; its core length only by mechanical considerations such as the permissible spacing apart of its bearings, etc.; and the loading of its windings only by magnetic reactions, such as selfinduction, field distortion, etc.; while due to the ability to employ light high current density windings for the rotor, the core diameter of the generator also can be increased if desired. And the resulting ability to employ the maximum speed, fluxspace, loading and current density for the generator, is thus seen to enable its design, construction and operation, for the maximum output, unit capacity and efliciency thereof as desirable.

While vacuum operation is best for high speed generators, all slow and medium speed machines of low windage loss, such as water driven generators, roll driving and othermotors, and also transformers, etc., can be operated without a vacuum, the pipe 9 and ejector 11 of the airtight casing then serving to discharge the water vapor therefrom to the atmosphere, and the same being thus operated at the atmospheric boiling point of about 212 F., with a Working temperature of about 225 F., while the superheated water would be supplied at about the temperature of 260 F. thereto.

And the only disadvantage of a slow or medium speed machine thus operated, as compared with the vacuum operation thereof, being a somewhat higher resistance loss in its windings, due to the higher Working temperature employed.

Having now fully described and explained my invention, as well as the most obvious applications thereof, I desire to state that the same is not closely limited to the apparatus and procedure described, which can be modified in various and obvious ways.

What I therefore claim as my invention is:

1. The method of cooling turbogenerators which comprises: forming a water mist at the temperature of the boiling point corresponding to the gaseous pressure in said generator, and supplying said mist to the generator and controlling its rate of formation and supply in such manner as to maintain the radiative temperature of the generator at a predetermined point above that of said boiling point.

2. The combination with a turbogenerator, of one or more spray pipes therein connected with a source of superheated water supply, for forming a water mist at 'the temperature of the boiling point in the generator, to absorb the heat losses by radiation at a temperature above that of said boiling point therefrom, and a valve in said supply pipe for admitting the superheated water to the generator at the rate required to maintain said superboiling point temperature therein.

3. The combination with a turbogenerator, of an airtight casing therefor and a vapor pipe connecting the same with the turbine condenser to obtain its vacuum therefor, also one or more steam jets in said pipe to eject the water vapor formed in ing generator, connected with a source of to raise the generator vacuum over that of the condenser, one or more spray pipes in the generator, connected with a source of superheated water supply, for forming a water mist at the temperature of the boiling point in the generator, to absorb the heat losses by radiation at a temperature above that of said boiling point therefrom, and a "alve in said supply pipe for admitting the superheated water to the generator, at the rate required to maintain said superboiling point temperature therein.

ALBERT W. SMITH. L. R. LEWIS, WM. E. McKEoHNrE.

Certificate of Correction.

It is herebv certified that in Letters Patent No. 1,502,065, granted July 22, 1924, upon the application of Albert Smith, of Los Angeles, Cahforrua, for an improvement in"Turbogenerators, errors appear in the printed spec ficat on requiring correction as follows: Page 3, l ne 1. for the word wlndings read windage; same page, claim 3, strike out line 77 and insert instead the words the generator to the condenser, and thus; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Qtiice.

Signed and sealed this 28th day [SEAL] of October, A. D. 1924. 

